/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | Copyright (C) 2011 OpenFOAM Foundation
     \\/     M anipulation  |
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.

    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.

    You should have received a copy of the GNU General Public License
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.

Class
    Foam::octree

Description
    Octree, templated on type of shapes it refers to.

    Uses the octreeData class, which is a list of 1D, 2D or 3D shapes.
    Various implementations of octreeData which know about cell&meshes,
    patches&meshes and points.

    The octree can be used to
      - find the "nearest" shape to a point
      - find the shape which contains a point (only sensible for 3D shapes)
      - find intersections of line with shapes

    The tree consists of
      - treeNode : holds sub-treeNodes or treeLeaves
      - treeLeaf : is the one that actually holds data

    The data is stored purely as a list of indices into octreeData.

    The construction on the depth of the tree is:
      - one can specify a minimum depth
        (though the tree will never be refined if all leaves contain <=1
         shapes)
      - after the minimum depth two statistics are used to decide further
        refinement:
        - average number of entries per leaf (leafRatio). Since inside a
          leaf most algorithms are n or n^2 this value has to be small.
        - average number of leaves a shape is in. Because of bounding boxes,
          a single shape can be in multiple leaves. If the bbs are large
          compared to the leaf size this multiplicity can become extremely
          large and will become larger with more levels.

    Note: the octree gets constructed with an overall bounding box. If your
    mesh is regular it is a good idea to make this overall bb a bit wider than
    the bb of the shapes itself. Otherwise lots of shapes end up exactly on the
    edge of a bb and hence go into more than one subcube.

    E.g. octree of face centres of lid driven cavity.

      -# bb exact -> total 1457 leaves (every point in 7.1 leaves)
      -# bb.max incremented by 1% -> total 80 leaves
         (every point in exactly 1 leaf)

    \par Ideas for parallel implementation:

    The data inserted into the octree (the
    'octreeData') has to be local to the processor. The data to be looked
    for (usually a sample point) can be global to the domain.
    The algorithm:
      - search for all my points
      - collect results which have to do with a processor patch
      - global sum all these. If 0 exit.
      - exchange data on all processor patches
      - start again

    So data transfers one processor per iteration. One could think of having
    an extra search mechanism one level above which does an initial search
    knowing the average shape of a processor distribution (square/cube for
    most decomposition methods) and can assign sample points to the (almost)
    correct processor at once.

SourceFiles
    octree.C

\*---------------------------------------------------------------------------*/

#ifndef octree_H
#define octree_H

#include "treeBoundBoxList.H"
#include "treeLeaf.H"
#include "pointIndexHit.H"
#include "linePointRef.H"

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

namespace Foam
{

// Forward declaration of classes
template<class Type> class treeNode;

// Forward declaration of friend functions and operators

template<class Type>
Ostream& operator<<(Ostream&, const octree<Type>&);


/*---------------------------------------------------------------------------*\
                        Class octreeName Declaration
\*---------------------------------------------------------------------------*/

TemplateName(octree);



/*---------------------------------------------------------------------------*\
                           Class octree Declaration
\*---------------------------------------------------------------------------*/

template <class Type>
class octree
:
    public octreeName
{
    // Private data

        //- Top treeNode. Modified by lower levels.
        treeNode<Type>* topNode_;

        //- all shapes
        const Type shapes_;

        //- Overall bb of octree
        const treeBoundBox octreeBb_;

        //- Refinement crit: size of leaves. Average number of entries per
        //  leaf. Should be fine enough for efficient searching at lowest level.
        const scalar maxLeafRatio_;

        //- Refinement crit: multiplicity of entries (so in how many leaves
        //  each shape is mentioned)
        const scalar maxShapeRatio_;

        //- Refinement crit: min no. of levels
        const label minNLevels_;

        //- Actual depth
        label deepestLevel_;

        //- Total number of (references to) shapes in octree
        //  (shapes can be stored in more than one treeLeaf)
        label nEntries_;

        //- Total number of treeNodes
        label nNodes_;

        //- Total number of treeLeaves
        label nLeaves_;


    // Static data members
        //- Refinement crit: max number of level
        static const label maxNLevels = 20;



    // Private Member Functions

public:

    // Data types

        //- volume types
        enum volumeType
        {
            UNKNOWN,
            MIXED,
            INSIDE,
            OUTSIDE
        };


    // Static data members

        //- for debugging:return printable representation of volumeType
        static string volType(const label);

        //- Code the vector with respect to the geometry. geomNormal guaranteed
        //  to point outside.
        static label getVolType
        (
            const vector& geomNormal,
            const vector& vec
        );

    // Constructors

        //- Construct from components
        octree
        (
            const treeBoundBox& octreeBb,
            const Type& shapes,
            const label minNLevels,     // minimum number of levels
            const scalar maxLeafRatio,  // max avg. size of leaves
            const scalar maxShapeRatio  // max avg. duplicity.
        );


    //- Destructor
    ~octree();


    // Member Functions

        // Access

            const Type& shapes() const
            {
                return shapes_;
            }

            const treeBoundBox& octreeBb() const
            {
                return octreeBb_;
            }

            scalar maxShapeRatio() const
            {
                return maxShapeRatio_;
            }

            scalar maxLeafRatio() const
            {
                return maxLeafRatio_;
            }

            label minNLevels() const
            {
                return minNLevels_;
            }

        // After construction: octree statistics

            treeNode<Type>* topNode() const
            {
                return topNode_;
            }

            label deepestLevel() const
            {
                return deepestLevel_;
            }

            label nEntries() const
            {
                return nEntries_;
            }

            label nNodes() const
            {
                return nNodes_;
            }

            label nLeaves() const
            {
                return nLeaves_;
            }

            void setEntries(const label n)
            {
                nEntries_ = n;
            }

            void setNodes(const label n)
            {
                nNodes_ = n;
            }

            void setLeaves(const label n)
            {
                nLeaves_ = n;
            }

        // Queries

            //- Returns type of sample with respect to nearest shape.
            //  Meaning of type is determined by shapes.getSampleType().
            //  Normally based on outwards pointing normal. For e.g.
            //  octreeDataFace returns one of
            //      inside  : on other side of normal on nearest face
            //      outside : on same side as normal on nearest face
            //      unknown : not above nearest face; surface probably not
            //                closed.
            //      mixed   : should never happen
            label getSampleType(const point& sample) const;

            //- Find shape containing point in tree
            //  Returns -1 if not in found. Uses Type::contains.
            label find(const point& sample) const;

            //- Calculate tightest fitting bounding box. Uses
            //  Type::findTightest.
            bool findTightest
            (
                const point& sample,
                treeBoundBox& tightest
            ) const;

            //- Find nearest shape. Returns index of shape or -1 if not found.
            //  tightestDist is both input and output. Uses Type::calcNearest.
            label findNearest
            (
                const point& sample,
                treeBoundBox& tightest,
                scalar& tightestDist
            ) const;

            //- Find nearest to line. Returns -1 or index of shape and
            //  sets:
            //  - tightest (is both input and output).
            //  - linePoint : point on line (-GREAT,-GREAT,-GREAT if not found)
            //  - shapePoint : point on shape (GREAT, GREAT, GREAT if not found)
            //  Uses Type::calcNearest.
            label findNearest
            (
                const linePointRef& ln,
                treeBoundBox& tightest,
                point& linePoint,
                point& shapePoint
            ) const;

            //- Find (in no particular order) indices of all shapes inside or
            //  overlapping bounding box (i.e. all shapes not outside box)
            labelList findBox(const boundBox& bb) const;

            //- Find intersected shape along line. pointIndexHit contains index
            //  of nearest shape intersected and the intersection point. Uses
            //  findLeafLine.
            pointIndexHit findLine(const point& start, const point& end) const;

            //- Like above but just tests whether line hits anything. So
            //   returns first intersection found, not nessecarily nearest.
            pointIndexHit findLineAny(const point& start, const point& end)
             const;

            //- Find leaf along line. Set leafIntPoint to leave point of
            //  treeLeaf.
            const treeLeaf<Type>* findLeafLine
            (
                const point& start,
                const point& end,
                point& leafIntPoint
            ) const;


        // Write

            //- Dump graphical representation in .obj format
            void writeOBJ(Ostream& os, label& vertNo) const;

            //- Print some stats on octree
            void printStats(Ostream& os) const;


    // STL iterator

        class iterator;
        friend class iterator;

        //- An STL iterator for octree
        class iterator
        {
            // Private data

                //- Reference to the octree this is an iterator for
                octree& octree_;

                //- List of pointers to treeLeaves
                List<treeLeaf<Type>*> leaves_;

                //- Current treeLeaf index
                label curLeaf_;

        public:

            //- Construct for a given octree
            iterator(octree&);

            //- Contruct for a given octree, at a certain position
            iterator(octree& oc, const label index);


            // Member operators

                void operator=(const iterator&);

                bool operator==(const iterator&) const;
                bool operator!=(const iterator&) const;

                treeLeaf<Type>& operator*();

                iterator& operator++();
                iterator operator++(int);
        };

        //- iterator set to the begining of the octree
        iterator begin();

        //- iterator set to beyond the end of the octree
        const iterator& end();


    // STL const_iterator

        class const_iterator;
        friend class const_iterator;

        //- An STL const_iterator for octree
        class const_iterator
        {
            // Private data

                //- Reference to the list this is an iterator for
                const octree& octree_;

                //- List of treeLeafs
                List<const treeLeaf<Type>*> leaves_;

                //- Current treeLeaf index
                label curLeaf_;

        public:

            //- Construct for a given octree
            const_iterator(const octree&);

            //- Construct for a given octree and index
            const_iterator(const octree&, label);

            // Member operators

                void operator=(const const_iterator&);

                bool operator==(const const_iterator&) const;
                bool operator!=(const const_iterator&) const;

                const treeLeaf<Type>& operator*();

                const_iterator& operator++();
                const_iterator operator++(int);
        };


        //- const_iterator set to the begining of the octree
        inline const_iterator begin() const;
        inline const_iterator cbegin() const;

        //- const_iterator set to beyond the end of the octree
        inline const const_iterator& end() const;
        inline const const_iterator& cend() const;


    // IOstream Operators

        friend Ostream& operator<< <Type>(Ostream&, const octree<Type>&);


private:

        //- iterator returned by end()
        iterator endIter_;

        //- const_iterator returned by end()
        const_iterator endConstIter_;
};


// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

} // End namespace Foam

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

#ifdef NoRepository
#   include "octree.C"
#endif

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

#endif

// ************************************************************************* //
